The 2 final missions alone are worth every penny.
One: Hard was just too easy. I never felt like it was much of a challenge. It needed a very hard or "action hero" difficulty.
Two: It just wasn't long enough. Completing everything on hard; Achievements, collectibles, side missions, and main campaign only took 9 hours. I think that had more to do with it being too easy. If it was harder (or if you just suck at video games) it would have take up to 15 hours or more.
I'm not sure why Ubisoft even bothered to make Far Cry 3 because this game is it's superior in every single way. Story, gameplay, visuals, and fun factor. The designers understood gaming to the max with this game. It's all about having fun and every single second of this game is incredibly fun. The cut scenes are hilarious, the animations are top notch, and the controls are fluid and enjoyable. I recommend this game to every single person who has ever enjoyed parodies, 80's action movies and cartoons, and true gamers everywhere. If your old enough you will reminisce consistently throughout your entire play through. It doesn't skimp out on anything 80's. The music and references are all there. Buy this, you will not regret a single second. I'll leave you with a quote.
Sloan: Your blood is blue just like mine, son.
Rex: You're wrong Sloan! My blood is red, white AND blue!